Adjunct for aluminum-cell lightning-arresters.



E. E P. GREIGHTON. ADJUNGT FOR ALUMINUM NEIL LIGHTNING ARRESTERS.

APPLICATION FILED AUG. 7, 1907.

Patented Sept, 1909.

W'tnesse UNITED STATES PATENT OFFICE. 1

ELMER E. F. CREIGHTON, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELEC- TRIO COMPANY, A CORPORATION OF NEW YORK.

ADJ'UNCT FOR ALUMINUM-CELL LIGHTNING-ABRESTER S.

Specification of Letters Patent. Patented Sept, 14, 1909. Application filed August 7, 1907. Serial No. 887,437.

.-' of New York, have invented certain new and useful Improvements in Adjuncts for Aluminum-Cell Lightnin'g-Arresters, of which the followin is a specification.

. This lnvention relates to lightning arresters of the electrolytic condenser type, such for instance as the one invented by me in which aluminum electrodes are immersed in an electrolytic such as ammonium borate. In an arrester of this type the resistance to the flow of the dynamic current which tends to follow a discharge of high potential, is due to the formation on the electrodes of a thin film of aluminum oxid or hydroxid.

Ordinarily this film is initially produced onthe aluminum plates by a forming process which consists essentially in subjecting the plates in a suitable electrolyte to the prolonged action of an electric current, usually an alternating current. After the films have once been formed and the apparatus has been assembled ready for use the electrolyte seems to act some way on the film and weaken or break it down in places.

quires an appreciable interval of time.

Therefore, when a circuit is established through an electrolytic cell, as by a high potential discharge, the cell may constitute more or less of a short circuit because of its deteriorated film, and a very undesirable surge may result. In order to maintain the high resistance qualities of the film, it is desirable for the station attendant to cut the cell into circuit periodically for a brief interval, in order to build up or re-form the film. However, unless some special provision is made, an undesirable surge may result by this very act, before the film can reform, which as will be understood, re-

In order to avoid this possibility of disturbing the system while repairing films, I place a small resistance in series with the aluminum electrode arrester, and so cut down the hi h initial current when the circuit is esta lished by the operator when closing the.

switch. The resistance need not be very great and is not objectionable for the pasdischarges-of 'reat quantit for which the resistance would offer an ohjectionable impedance, I place aspark ap in parallel with the resistances. Such discharges can then ground without going through the resistance.

The accompanying ,drawing is a diagram illustrating my invention in connection with 'a single phase distribution circuit.

The aluminum electrode lightning arrester 1, is connected between line 2 and ground 3'in series with a short spark ap 4t and a somewhat longer gap 5. A switc 6 is placed in shunt with the spark gap 5. The spark gap 4 is shunted by the non-inductive resistances 7. The arrester 8 is similarly connected between line 9 and ground 3, through gaps 10 and 11, which are shunted by resistance 12 and switch 13 respectively. It will be seen that by the simultaneous closure of the switches 6 and 13, a complete circuit exists from line to line, through switch 6, resistance 7, arrester 1, .ground, arrester 8, resistance 12 and switch 13. The resistances 7 and 12 prevent a surgeon the line when the-switches are closed and before the films have had time to reform on the aluminum plates. As before explained, a large percentage of lightning strokes will discharge 'Without difiiculty through the resistances 7 and 12 in the ordinary operation of the lightning arrester, while the spark gaps 4 by Letters Patent of the United States, is,

1. The combination with an electrolytic condenser lightning arrester, of a resistance in series therewith, and a high-resistance shunt in parallel with said resistance.

2. The combination with an electrolytic condenser lightning arrester, of a resistance in series therewith, and a spark-gap in parallel with said resistance.

3. The combination with an electrolytic condenser lightning arrester, of a switch for connecting it to line, a resistance in series with said arrester, and a spark-gap in shunt to said resistance.

4. The combination of a line conductor of a transmission system, an electrolytic lightning arrester, a resistance arranged to be included at will in circuit with the arresterbetween the line conductor and ground, and a low inductance path in parallel with said 'ibetween line and line, a low inductance path resistance.

' 5. In combination with line conductors of a transmission system, an electrolytic lightnin arrester, a resistance, a low inductance path in parallel with said resistance, and switching means for including the resistance in circuit with the arrester between line and line.

6. The combination of line conductors of a transmission system, an electrolytic lightning arrester connected to each of said conductors in series with a s ark gap, ground connections for each of said arresters, a resistance in the path. through the arresters in parallel with said resistance, and means for brldging the spark gaps in the circuits of the arresters between line and line.

7. The combination with an electrolytic 20 ELMER E. F. CREIGHTON.

Witnesses:

LEONARD VVILSON, J. MLDE LANDER. 

